The present invention relates to a technique for suppressing energy radiated from an antenna device, and particularly relates to a technique for preventing electromagnetic wave from giving a user a risk of injuring the operator's health when such an antenna device is mounted on a portable radio communication apparatus such as a satellite portable telephone, etc.
In recent years, ideas of satellite portable telephones using satellites revolving around the earth in a low or intermediate orbit have been proposed from various companies. With respect to frequency bands therefor, there are two satellite communication protocols. In one protocol, a 1.6 GHz band is allocated to communication from a ground satellite portable telephone to a satellite and a 2.4 GHz band is allocated to communication from the satellite to the ground satellite portable telephone. In the other protocol, a 1.6 GHz band is allocated to two-way communication from the ground to the satellite and from the satellite to the ground. Most of satellite communication systems use circularly polarized wave.
In recent years, there are opinions which point out a risk of electromagnetic wave injuring health of users of portable telephones. Although the causal relationship between electromagnetic wave and health injury is unknown at present, a technique for preventing electromagnetic wave from giving users a risk of injuring their heath should be established for accomplishment of satellite communication in a portable telephone transmitting electromagnetic wave toward the satellite.